The present invention relates to water jet propulsive devices of drives which can be used for example in floating means, pumps and the like.
Water jet propulsive devices are well known and designed as centrifugal or axial propulsive devices with a rotor, a water passage, a pump part and a nozzle. A water inlet is located always below a waterline, and thereby a water passage has a turning bend for introducing the pump shaft, or several bends. The known water jet propulsive devices have several disadvantages. For efficient operation a high speed of blades is required, which leads to cavitation. The devices are complicated due to introduction of the shaft into the water passage pipe, complicated shape of the water passage pipe for its connection with the pump and the shaft, and a system of connecting of successive stages in the axial drive and parallel stages in the centrifugal drive. The devices have considerable size due to several stages arranged successively in the axial devices and parallel in the centrifugal devices. Finally, the devices have high hydraulic losses since it is necessary to raise water above a waterline and urge it through bent passages. One of such devices is disclosed in the U.S. Pat. No. 4,735,045, which also has the above disadvantages. It is to be understood that it is desirable to propose water jet propulsive devices which avoid such disadvantages.